Antenna Deembedding in WBAN Channel Modeling Using Spherical Wave Functions

Body area network (BAN) is a fundamental technology to realize future ICT-based healthcare services and applications, where channel modeling plays an important role in designing more reliable BAN systems. The greatest challenge of the WBAN channel modeling is that the antennas operate in proximity to the human body. Near-field interactions between the antenna and the human body make it difficult to distinguish the contribution of the antennas within the channel response, i.e., the antennas are embedded in the channel. As a result, the characterized channels had to be always specific to the given antenna, and antenna optimization is difficult. Therefore, this paper proposed antenna deembedding by applying the spherical wave function channel modeling into the on-body channel. The finite-difference time-domain (FDTD) method was utilized to implement the concept. The proposed implementation was validated against the conventional antenna-embedded simulation. Furthermore, the antenna performance evaluation in terms of mean path gain during a specific body motion was demonstrated as an application. The simplified but practical version of the proposed approach, involving only the fundamental modes, was introduced. The obtained mean path gain was compared with the measurement.